Question

A hot electric iron has a resistance of $80\, \Omega$ and is used on a $200\, V$ source. The electrical energy spent, if it is used for $2\, hr$, will be :

• A. 8000 Wh
• B. 2000 Wh
• C. 1000 Wh
• D. 800 Wh

Answer 1

Answer: (C)

1000 Wh

Answer 2

Here : Resistance $R =80 \Omega$ Voltage $V =200\, V$ Time $t =2\, hr$ Voltage $V=200\, V$ The relation of power is given by $P=\frac{V^{2}}{R}=\frac{(200)^{2}}{80}=500\, W$ Hence, energy spent is given by =power $\times$ time $=500 \times 2=1000\, Wh$